1. Field of the Invention
The invention relates to the field of acquiring manufacturing process data on a part-by-part basis (e.g. chip), and more specifically, to providing a means to acquire device data with which to perform a detailed product analysis, which is further used to tune the manufacturing processes.
2. Background of the Invention
Due to the complex and precise nature of semiconductor manufacturing, it is critical to ensure that all processes in the manufacturing line are within required specifications. This ensures the highest product yield. Monitoring the manufacturing process and correcting for deficiencies is critical for maintaining the health of the line (HOL).
Some testing is done in-line during manufacturing to tune the process real-time, and other tests are performed after manufacturing. Kerf testing is a common type of testing and provides information for a group of die on a wafer relating to process, voltage, and temperature (PVT). Other tests include: I/O receiver/driver levels, performance screen ring oscillator (PSRO) testing, and MUX scan testing, also known as “at speed” testing.
The problem with kerf testing is that it does not provide detailed information specific to each die on the wafer and further, cannot provide information about the electrical parameters of certain devices within each of the chips; especially custom designs which have smaller manufacturing lot sizes, device dimensions which vary from standard devices, and other product-specific qualities.
Since in-line testing is time consuming and expensive, it is important to perform adequate testing within a minimal amount of time. Generally, testing is done by sampling a set of kerfs to obtain an overall HOL measurement. For customized circuits, such as application specific integrated circuits (ASIC) testing by sampling does not provide an accurate assessment of device parameters within each die of the wafer. Maintaining device parameters within specifications is critical for improving yield and ensuring that customer requirements and delivery expectations are met.